Gaze entropy metrics for mental workload estimation are heterogenous during hands-off level 2 automation

As the level of vehicle automation increases, drivers are more likely to engage in non-driving related tasks which take their hands, eyes, and/or mind away from the driving task. Consequently, there has been increased interest in creating Driver Monitoring Systems (DMS) that are valid and reliable for detecting elements of driver state. Workload is one element of driver state that has remained elusive within the literature. Whilst there has been promising work in estimating mental workload using gaze-based metrics, the literature has placed too much emphasis on point estimate differences. Whilst these are useful for establishing whether effects exist, they ignore the inherent variability within individuals and between different drivers. The current work builds on this by using a Bayesian distributional modelling approach to quantify the within and between participants variability in Information Theoretical gaze metrics. Drivers (N = 38) undertook two experimental drives in hands-off Level 2 automation with their hands and feet away from operational controls. During both drives, their priority was to monitor the road before a critical takeover. During one drive participants had to complete a secondary cognitive task (2-back) during the hands-off Level 2 automation. Changes in Stationary Gaze Entropy and Gaze Transition Entropy were assessed for conditions with and without the 2-back to investigate whether consistent differences between workload conditions could be found across the sample. Stationary Gaze Entropy proved a reliable indicator of mental workload; 92 % of the population were predicted to show a decrease when completing 2-back during hands-off Level 2 automated driving. Conversely, Gaze Transition Entropy showed substantial heterogeneity; only 66 % of the population were predicted to have similar decreases. Furthermore, age was a strong predictor of the heterogeneity of the average causal effect that high mental workload had on eye movements. These results indicate that, whilst certain elements of Information Theoretic metrics can be used to estimate mental workload by DMS, future research needs to focus on the heterogeneity of these processes. Understanding this heterogeneity has important implications toward the design of future DMS and thus the safety of drivers using automated vehicle functions. It must be ensured that metrics used to detect mental workload are valid (accurately detecting a particular driver state) as well as reliable (consistently detecting this driver state across a population).

The effect of information from dash-based human-machine interfaces on drivers' gaze patterns and lane-change manoeuvres after conditionally automated driving

The goal of this paper was to measure the effect of Human-Machine Interface (HMI) information and guidance on drivers' gaze and takeover behaviour during transitions of control from automation. The motivation for this study came from a gap in the literature, where previous research reports improved performance of drivers' takeover based on HMI information, without considering its effect on drivers' visual attention distribution, and how drivers also use the information available in the environment to guide their response. This driving simulator study investigated drivers' lane-changing behaviour after resumption of control from automation. Different levels of information were provided on a dash-based HMI, prior to each lane change, to investigate how drivers distribute their attention between the surrounding environment and the HMI. The difficulty of the lane change was also manipulated by controlling the position of approaching vehicles in drivers' offside lane. Results indicated that drivers' decision-making time was sensitive to the presence of nearby vehicles in the offside lane, but not directly influenced by the information on the HMI. In terms of gaze behaviour, the closer the position of vehicles in the offside lane, the longer drivers looked in that direction. Drivers looked more at the HMI, and less towards the road centre, when the HMI presented information about automation status, and included an advisory message indicating it was safe to change lane. Machine learning techniques showed a strong relationship between drivers' gaze to the information presented on the HMI, and decision-making time (DMT). These results contribute to our understanding of HMI design for automated vehicles, by demonstrating the attentional costs of an overly-informative HMI, and that drivers still rely on environmental information to perform a lane-change, even when the same information can be acquired by the HMI of the vehicle.

Endothelial cell dysfunction correlates differentially with survival in primary and secondary pulmonary hypertension

BACKGROUND

Plasma von Willebrand factor antigen (vWF:Ag) has been used as a marker of endothelial perturbation in a number of vascular disorders. In this study, vWF:Ag was determined as an attempt to evaluate the severity of endothelial cell dysfunction in primary pulmonary hypertension (PPH) and congenital heart disease-associated pulmonary hypertension (CHD-PH) comparatively and to determine its impact on short-term survival.

METHODS AND RESULTS

Clinical, hemodynamic, and biochemical data were obtained from 11 patients with PPH and 24 with CHD-PH. Patient groups were similar in terms of age and pulmonary artery pressure. vWF:Ag was measured by electroimmunodiffusion. Patients were followed up for 1 year and at that time, data collected at the beginning of the study were subjected to univariate and multivariate analyses. vWF:Ag was increased in patients (normal reference value 87% +/- 23% activity, mean +/- SD), with higher levels in the PPH group (231% +/- 89%) in comparison with the CHD-PH group (127% +/- 68%) (P <.001). Multivariate analysis showed that survival was influenced by the underlying cause of pulmonary hypertension and vWF:Ag levels but not by patient age, sex, or pulmonary artery pressure. Seven of 10 nonsurvivors but only 4 of 25 survivors had PPH (P =.007). vWF:Ag was 255% +/- 90% in the nonsurvivor group and 121% +/- 54% in the survivors (P <.001).

CONCLUSIONS

Our findings suggest that short-term survival is related to the severity of endothelial cell dysfunction in pulmonary hypertension. In addition, exceedingly high vWF:Ag levels in PPH might reflect a particular pattern of endothelial cell dysfunction that could be associated with decreased short-term life expectancy in this disorder compared with secondary forms of pulmonary hypertension.

[The joint hospitalization of mother and child at the Hospital das Clínicas of the State University of Campinas. The assessment of a group of mothers]

This investigation is a field study involving 84 mothers who participated in the rooming-in program in the Pediatric Ward at the University Hospital of UNICAMP, Campinas São Paulo. The purpose of the study was to identify the mother's opinions concerning the hospitalization of their children under the rooming-in program, as well as to make a contribution towards the improvement of planned nursing care in the Pediatric Unit. Data collection was obtained through the use of a structured interview with each mother. The interview form included some mother's opinions concerning rooming-in. The results showed that these mothers considered the rooming-in program important for the treatment of the child, and that they related as "good" and "excellent" about care given in the unit.

Regional heart wall motion: two-dimensional analysis and functional imaging with MR imaging

Analysis of the transmural distribution or nonradial components of myocardial motion has previously been possible only with use of invasive techniques such as implantation of radiopaque markers. Magnetic tagging of the heart wall in conjunction with magnetic resonance imaging allows noninvasive regional analysis of within-wall motion, including its separation into components of rigid body motion and deformation. The results of this analysis can be displayed as functional images. This provides a new tool for the study of heart wall motion that should be of use for both basic physiologic and clinical research applications.

[Treatment using balloon catheterization of pulmonary valve stenosis]

From October 84 to September 88 we performed pulmonary valvuloplasty with balloon catheter (PVBC) in 90 patients (pt) with pulmonary valve stenosis (PVS). The patients were divided in 3 groups (Gr) by their ages: group I (Gr. I) 7 pt (8%) aged 4 days to 11 months, Gr. II 66 pt (73%) aged 1 year to 12 years and Gr. III 17 pt aged 13 to 34 years. This study consists of clinical and echocardiographic evaluation adopting the following parameters of indication: a) transvalvar pulmonary gradient (G); b) absence of dysplasia or hypoplasia of the pulmonary annulus. There were associated lesions which were found in each group: Gr. I atrial septal defect (ASD) in 2 pt and tricuspid insufficiency (TI) in 1 pt, in Gr. II supra valvar stenosis (SVS) in 1 pt and patent arterial ductus (PAD) in 1 pt and in the Gr. III (ASD) in 1 pt. The results after pulmonary valvuloplasty with balloon catheter (PVBC) were: (Gr.I) in 5 pt the G were reduced below 50 mmHg and the average of right ventricular systolic pressure (RVSP) changed from 92 to 62 mmHg and the average of G from 76 to 44 mmHg. One of these pt was submitted to surgery 1 month after the procedure and 2 developed restenosis in 2 and 3 years respectively, being submitted to another dilatation with good results. The 2 pt in which the procedure was not effective were submitted to surgery. In the second group the PVBC was effective in 61 pt (92%) showing the RVSP changed from 118 to 64 mmHg and G changed from 86 to 23 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)